What difference are you wondering about? You will see a significant difference between Blu-Ray discs vs. regular DVD's. The PS3 is also a good upscaler for DVD's, so the visual quality for those should increase as well (unless you already have a good upscaling DVD player).
I currently have a Panasonic TH-50PX77U and was thinking about getting a PS3 for it (I currently have a Denon 2910). Will the difference be significant or will I barely notice it? Will my TV even be able to process a Blu-ray disc?